Abstract: Optical coatings in a laser system are easily damaged, so it is important to investigate the temperature field of the film irradiated by a long-pulse laser. A spatial axisymmetric finite element model of single layer HfO2 film with a high-absorptance platinum inclusion was used to study the thermal damage induced by a long-pulse laser. Influences on the temperatures of the film and substrate by the absorption coefficient and the depth of the platinum inclusion in the film were analyzed. The results show that the maximum temperature in film surface, compared with pure HfO2 film, can be increased more than one time when the depth of inclusion is 100nm; when the depth of inclusion reaches 750 nm, the temperature of substrate is higher than that of film, which may cause first damage of the substrate. Results of the research can provide a reference for optical film design in the preparation and preprocessing of thin film applied in the long-pulse system.